Compass-deviation corrector.



PATENTED MAY 23, 1905.

B. H. CAMDEN. COMPASS DEVIATION GORRECTOR.

APPLIOATION FILED JUNE 11. 1904.

Patented May 23, 1905.

ATENT FFIQE.

BERNARD H. CAMDEN, OF THE UNITED STATES REVENUE SERVICE, AS-

SIGN OR, BY DIRECT AND MESNE ASSIGNMENTS, OF SEVEN-EIGHTHS TO HARRY PEYTON ARBECAW, OF BOSTON, MASSACHUSETTS, AND ONE- EIGHTH TO EDITH S. HOLDEN, OF BOSTON, MASSACHUSETTS.

COIVIPASS-DEVIATION CORRECTOR- SPECIFICATION forming part of Letters Patent No. 790,871, dated M y 23, 1905.

Application filed Tune 11, 1904:. Serial No. 212,071.

To all whom, it ntru concern:

Boit known that I, BERNARD H. CAMDEN, of the United States Steamship Seminole, in the United States Revenue Service, have invented certain new and useful Improvements in Compass-Deviation Correctors, of which the following is a specification.

It is well known to mariners that the magnetic needle at times deviates slightly from IO the true meridian, (to a greater or less extent under different circumstances,) and it has heretofore been necessary after taking observations by compass to correct 'the same by a mathematical calculation, making allowance 5 for the known deviation.

The object of my invention is to provide a simple device applicable to a ships binnacle for correcting the deviation of the compass, so as to show at a glance and without a scientific computation the true magnetic bearing of objects within the range of vision.

In'the drawings, Figure 1 is an elevation,

partly in section, of a binnacle furnished with a sighting-tube and alidade and having my im- 5 provement applied to the vertical shaft or stem. Fig. 2 is a top plan showing my device and the compass-dial on a larger scale, the shaft or stem in section'on line 2 2 of Fig. 1. Figs. 3 and 4 are enlarged sectional details 3 illustrating my improvement.

The binnacle l and compass-dial 2 will be of suitable form. A vertical shaft 3, mounted for rotation in the binnacle-t'op, carries at its upper end a sighting-tube 4 and at its foot a radial indicator 5, the tip of which rests lightly on the dial. Tube 4 and indicator 5 are pivoted to shaft 3 and extend normally in the same vertical plane, so that the indicator shows on the compass-dial 2 the precise point 4 of the compass on which the sighting-tube bears, as in the well-known Arbecam alidade. To a structure of this general character I apply my deviation-Corrector, in which 6 represents a radial pointer screwed into or other- \vise firmly secured to the upper section of shaft 3, and 7 is a flat horizontal sector-plate immediately below pointer 6 and formed with a depending circular flange 8, by which said plate is secured to a sleeve 9, surrounding the shaft, and held adjustably thereon by set- 5 screws 10. The sector-plate has near its outer end a short are graduated in degrees or points and fractions thereof, as at E. W., Fig. 2.

Within sleeve 9 the vertical shaft is in two separate sections one above the other, the sleeve and its set-screws serving to couple them together. Said sleeve has a recess or transverse slot 11 formed through it just above the sector-plate 7 to permit insertion of the threaded end of pointer 6 into shaft 3 and allow the pointer a limited lateral movement in adjusting it for deviation.

When there is no deviation, the sightingtube 4:, the indicator 5, and the intermediate pointer6 all radiate in the same vertical plane, 5 the pointer extending over the center of sector-plate 7. In case of deviation, the amount I being known, loosenthe upper thumb-screw l0 and swing the pointer, and with it the sighting-tube, through the angle equal to the 7 O deviation to east or west, as-denoted by E. and IN. on said plate, Fig. 2, then tighten said thumb-screw,and take the bearings as denoted by indicator 5, which will be true magnetic ones. 7 5

I claim as my invention 1. A binnacle, acompass and its dial therein,

a rotatable sectional shaft supported vertically by the binnacle and provided, terminally, with a sighting device and radial indicator normally maintained in the same vertical plane, in combination with a horizontal sector-plate graduated terminally and a radial pointer above and adjacent to said plate, at an intermediate point on said shaft, said pointer 5 and sighting device being angularly adjustable with relation to said sector-plate and indicator to an extent equal to the known deviation of the compass, for the purpose set forth. 9

2. The described compass-deviation corrector, comprising an alidade having a vertical central shaft in tWo sections respectively ment of said plate and pointer, substantially 1'0 carrying a sighting-tube and compass-indicaas set forth.

tor, normally in the same radial vertical plane, In testimony whereof I have affixed my sigin combination with a radial pointer fixed in nature in presence of two Witnesses.

5 the upper section of said shaft and ahorizontal sector-plate furnished terminally With a short graduated arc beneath said pointer, and Witnesses: With a sleeve surrounding said shaft, secured A. H. SPENCER, to said plate and recessed for relative adjust- H. W. LADD.

BERNARD H. CAMDEN. 

